A requirement for a security barrier was announced by the US Border Patrol. They needed a barrier able to be built from readily available materials. Further, it must be easy to build (not requiring skilled labor) and modular to adapt to varying local conditions and changing scenarios. A preferred embodiment of the present invention is designed for use under various applications. Thus, initial design criteria were based upon the needs of the U.S. Border Patrol for a barrier to use under a variety of conditions to control border access. Criteria included:
It must be solid to hamper the passing of drugs across it and prevent penetration of bullets to the other side.
It must be robust against degradation of its function while maintaining its structural integrity. Degradation sources include scaling, burrowing under, ramming by vehicles, cutting, and repeated hammering and chipping.
It must inhibit immediate traversal to facilitate apprehension of the transgressor.
It must be maintained at relatively low cost with maintenance easy to perform quickly in order to minimize exposure of maintenance personnel.
It must be usable in all types of geography, including hilly and rough terrain.
It must xe2x80x9cwork well and last a long timexe2x80x9d irrespective of the type and frequency of repairs.
It must minimize the danger to the Border Patrol and other personnel working at the border.
Because the Border Patrol cannot control what is done on the xe2x80x9cforeign sidexe2x80x9d of the barrier, design criteria must account for this limitation. Of course, such a barrier might be adapted for other uses, especially those for which less stringent requirements may exist.
Previous barrier designs used to aid the Border Patrol have failed to control access across the border. Various designs of wire mesh fences, commonly used in prisons and schools, have been easily destroyed by transgressors. A barrier constructed from surplus temporary airfield landing mat is currently installed between San Diego, Calif. and Tijuana, Mexico. On the southern border with Mexico, fencing is installed only near population centers. Hence, only as many as 98 Km (60 miles) of the more than 3100 Km (1900 miles) is fenced. The excess steel landing mat will be exhausted long before any significant amount of border is fenced. The steel landing mat barrier is difficult to maintain and is easily circumvented by scaling or digging under the fence, sawing, use of a cutting torch, ramming, etc.
A bollard fence design has been installed as both a primary and secondary barrier (a second barrier located north of the primary barrier) at the same location. This bollard fence is a staggered line of vertically oriented concrete posts spaced at 10-12.7 cm (4-5 inches) and embedded in concrete. The posts are vulnerable to chipping, require concrete forms that must be installed by skilled contractors, and may be vandalized easily while curing. Transgressors can both see through and reach through the bollards, allowing them to pass drugs and even shoot through them. Proposals to enclose the bollards in steel tubes may make them less vulnerable to attack. This still allows transgressors to reach through the fence and still requires skilled contractors to construct and repair them.
In selected areas there are also impediments at low heights for deterring vehicle traffic. A fence has been installed between El Paso, Tex. and Mexico that is aesthetically appealing, but not resistant to vandalism. The fence is constructed of lightweight panels a few inches thick, mounted on support poles a few inches in diameter. Attacks by blunt instruments can easily create gaping holes in the fence. Ramming by a vehicle can severely damage the fence. In addition, resultant openings allow transgressors to transfer illicit items.
Existing designs fail to meet needs of the Border Patrol at a reasonable cost over their life cycle. A preferred embodiment of the present invention provides a cost effective solid barrier to human and vehicular intrusion that meets all the requirements of the Border Patrol and similarly situated agencies and organizations and may be adapted for commercial or consumer use.
An embodiment of the present invention provides a method of deployment for an economical multi-purpose barrier in applications such as a primary barrier at an international border, security for military installations, and general security, safety or privacy applications in police, industrial, recreational, commercial, environmental, or residential applications. In one embodiment, the method provides a barrier that is solid and highly resistant to damage. In an embodiment of the present invention the method provides a barrier that combines the properties of a high strength panel, such as steel or a high strength polymer, and a masonry wall, such as concrete or pumice-crete. The exterior of this barrier is comprised of interlocking panels that serve as:
armor against attack (both above and below grade);
enclosures for in-fill material, such as fill dirt, sand, or concrete; and
a mechanism for transferring an external force applied against any individual section to neighboring sections.
In this barrier, the exterior panels have interlocking joints that resist physical intrusion without the addition of in-fill material. The addition of in-fill material provides additional support for the connections, thus providing additional protection against attack. Besides providing additional mass against ramming, solid in-fill also provides a formidable barrier against intrusion should exterior panels be removed or damaged. The external panels may be embedded in the ground, providing significant resistance to ramming, tipping, or burrowing beneath the barrier. Additionally, the barrier may be anchored internally to resist tipping; forces applied near its top.
A barrier deployed via a method of the present invention is installed quickly and easily. Further, should the need arise, it may be repaired without the need of special tools, heavy equipment, or concrete forms. In one embodiment of the present invention, a trench of suitable dimensions, such as approximately 0.9 m (3 ft) deep by 1.6 m (5 ft) wide, is dug the length of the section to be installed or the length of a reasonable portion of the entire boundary desired to be protected. After emplacing and connecting panel sections in the trench, a suitable in-fill material, such as concrete, is placed between the panels. To hold a cementitious mixture until setup, a temporary removable form may be used at one or both ends of a suitable length comprising one or more sections of the barrier. This form may be used with suitable soft material and left in place to comprise an expansion joint for the concrete. Deterrents may be affixed to the top of a completed section and secured on the xe2x80x9cprotectedxe2x80x9d side of the barrier by suitable means, such as welding, epoxy, mechanical fasteners, or combinations thereof. Alternatively, pre-connected (xe2x80x9cprotectedxe2x80x9d side and xe2x80x9ctransgressorxe2x80x9d side) sections can be dropped into place in a trench as needed, the trench backfilled quickly, and the resultant barrier serve the same purpose as an xe2x80x9cin-filledxe2x80x9d section, at least temporarily.
Advantages of a preferred embodiment of the present invention that provides maximum resistance to an aggressive transgressor include:
prevents ready ingress by surface or sub-surface based transgressor;
requires greater effort and more time to breach than conventional designs;
makes penetration by a welding torch, chipping, cutting, or other mechanical means difficult and time-consuming;
provides no purchase for a person to breach the top from either direction because of its smooth barrier walls extending high above the ground at a steep angle since there are no external connections needed to be made when installing the panels;
prevents transgressors from using it to survey an area because of the narrow width at its top together with optional detectors and deterrents that may be placed at its top;
optional deterrents may be used based on specific needs, locations, times and expected transgressors;
optional deterrents affixed to the top of a high version require a transgressor to work at an unsafe height at a risk of serious injury from a fall;
detectors and deterrents may be repaired on the protected side of the barrier below its maximum height, thus, shielding the workers from potential transgressors;
detectors and deterrents may not require urgent repair since the height, shape and texture of the barrier makes breaching more difficult than conventional systems;
repairs can be postponed since defeating the barrier""s purpose requires both panels and the in-fill material to be removed or damaged;
use of interlocking high strength panels as permanent forms for the in-fill material and as a structural member of the barrier facilitates both rapid installation and rapid repair of the barrier;
may be installed over existing barriers, resulting in a barrier that uses existing structure as part of its xe2x80x9cin-fillxe2x80x9d material for providing added strength without incurring time and expense to remove the existing system; and
replacement panels may be welded or epoxied over any gaps in the barrier caused by major damage from sophisticated transgressors and new in-fill material quickly added to re-establish barrier integrity.
Further, all embodiments share the following advantages:
can be assembled easily by workers needing no special skills;
low maintenance costs;
increased flexibility for use so that a less durable design may be applied to commercial, environmental, industrial or even residential use;
high reliability;
simplified design of alternate configurations to include mobile or temporary installations;
ability to use different modules at the top to meet specific requirements as they arise; and
ready upgradability to state-of-the-art modifications.
The design of a preferred embodiment of the present invention makes it adaptable in applications where conventional barriers cannot be used effectively, easily or economically. The simple design of the barrier allows the substitution of existing local materials for in-fill material in the construction of the barrier body. For example, sheet pile may be substituted for a panel. Rebar can replace connecting rods. Very large nuts or steel pipes cut into small sections can be welded to the panels to act as the connection between the connecting rods and panels. Where little or no in-fill material is used, the connecting rods can be oriented diagonally and secured with turnbuckles that can be locked down using double nuts. If sheet pile were attached or changed, the only design adjustment needed is the adaptation of the cover shell to the sheet pile shape.
Various intrusion detectors and deterrents may be attached to a barrier deployed using a preferred embodiment of the present invention so that it may be adapted readily to changing threats. Detectors and deterrents may include: wire mesh extensions; various detectors including pressure sensitive, motion, infrared, electromagnetic, and combinations thereof; surveillance devices using video, audio, RF and optical bands; and razor or whip wires. Further, anti-personnel deterrents such as pepper spray or o-chlorobenzylidene malononitrile (CS gas) could be activated by sensors. Military applications may use the same assortment as above and include detectors attached to lethal anti-personnel devices and shielded enclosures for use by heavily armed military personnel. In a commercial or residential setting, decorative plants may be added along the top. Further, in some applications where in-fill material is not used or used to fill only part of the void, parts of the panels used on sections of the barrier may be designed to be opened along one side for access to controls for deterrents or for storage of items such as tools, hoses, fertilizer, swimming pool equipment, etc.
Specific applications of a barrier deployed with a method of the present invention include vehicular barriers to deter terrorist car bomb attacks and a barrier rapidly constructed for use by the military in combat. The ability to construct a barrier using unskilled labor and to fill it with dirt, sand or stabilized earth (i.e., a bag of Portland cement is added to each cubic yard of dirt) makes it practical for military use where there may be limited availability of heavy equipment or concrete. Using a hardened filler, such as concrete or pumicecrete as formulated in U.S. Pat. No. 4,373,955, Lightweight Insulating Concrete, issued to Bouchard et al., the barrier is resistant to conventional munitions, such as bullets, shell shrapnel, and non-armor piercing shells. Further, a properly anchored barrier of appropriate size may prevent tracked vehicles from crossing the barrier unless an inordinate amount of time is taken to demolish it beforehand. Additionally, a barrier may be installed over existing barriers. This results in a barrier that did not incur the cost of demolition of an existing ineffective or damaged barrier but can use this existing structure as part of its xe2x80x9cin-fillxe2x80x9d material for providing added strength. At the opposite end of its application spectrum, a barrier may be used to contain domestic animals and pets or even as a part of a fence with built-in storage for a residence in an urban setting.